A teenager who claims to have sold his soul to the devil is now being charged with a murder investigators describe at "sadistic" and brutal.

Jose Reyes, 17, is one of two teens charged in the murder of a 15-year-old girl. On Tuesday, we learned more about the charges against him. A warning -- some of the details are very graphic.

Prosecutors say Reyes confessed that he and his 16-year-old accomplice did it as a satanic ritual.

Shackled, Reyes walked into courtroom, taking a brief look around before going in front of the judge.

According to the state, sometime Wednesday evening, Reyes and his 16-year-old accomplice showed up to a vacant apartment on El Camino Real with 15-year-old Corriann Cervantes.

Prosecutors say Reyes admitted to hitting Cervantes in the head with an ashtray. And according to prosecutors, when she yelled, 'Why are you doing this to me?" they held her to keep her from escaping.

The state says the two suspects then began sexually assaulting her and stabbed her in the face with a screwdriver. The state says she was left mutilated with an upside-down cross carved in her stomach.

"Mr. Reyes and the juvenile were in the vacant apartment with the 15-year-old complainant, that they discussed the fact that Mr. Reyes sold his soul to the devil and if they ended up killing this teenager, this would allow the 16-year-old to also sell his soul to the devil," said prosecutor John Jordan. "They hit her with an ashtray, with the lid of a commode. What happened in that vacant apartment was sadistic. What will eventually happen in the 338th courtroom will be justice."

Reyes and the juvenile are both charged with capital murder. We learned on Tuesday from prosecutors that Reyes' own family turned him in. That juvenile has reportedly given a recorded confession and is scheduled back in court Wednesday for a detention hearing.